Here is a DM you can copy word for word and send to agencies today.
Hi [name], I saw you are running ads for [offer]. Quick one. I help agencies book more calls by sending personalized Loom videos to their dream prospects, and I would love to do a few test Looms for you for free. If they are good, we talk. If not, no harm done. Worth a shot?
Why this works.
It is short. It mentions something specific about them. It removes all risk with the free test. And the close is soft.
Send 10 of these a day. You will get replies. Beginners overthink this part. Volume plus a decent script beats a perfect script sent twice.